Rafael Benítez has reignited his long-running feud with Sir Alex Ferguson, hitting out at the Manchester United manager for failing to shake his hand before the start of Chelsea's 2-2 FA Cup quarter-final draw at Old Trafford.

Benítez made a pointed reference to his "education" as he claimed he had tried to greet his rival only to be snubbed. After the match Chelsea's interim manager walked on to the pitch to congratulate his players on coming from two goals down, without waiting to shake hands with Ferguson.

Wayne Rooney, dropped for last Tuesday's Champions League defeat by Real Madrid, was restored to the United side and scored on 11 minutes to double their advantage after Javier Hernández's earlier goal. But what appeared a triumphant return for the Liverpudlian was spoiled by second-half goals from Eden Hazard and Ramires to take the tie to a replay.

When the replay will be played has not been decided due to fixture congestion compounded by Chelsea's Europa League commitments and two consecutive weeks with international matches. The winners will play Manchester City.

Benítez, asked why he had not shaken hands with Ferguson at the finish, said: "I was waiting – I was waiting at the beginning [of the match]." Had Ferguson walked past him? "Yeah. It's his decision. I was ready and waiting [to shake], I have some education. I was waiting, I have education because I know that a lot of people are watching so I know what I have to do."

Elaborating on why he had not greeted Ferguson at the end, he said: "I was with my players celebrating."

United's Rio Ferdinand may face a Football Association charge after he seemed to foul Fernando Torres off the ball by pushing a hand into the striker's neck and placing his boot into the back of him. If Howard Webb, the referee, did not see the incident and fails to mention it in his match report, then the FA may charge Ferdinand. He would face a potential three-match ban.

Benítez, in response to whether he saw the incident, said: "See the replay [yourself]." What was his take on it? "I haven't seen it but you can see the replay; you have an advantage."

Torres did, though, mention it to Benítez. "Yes. But you can see the replay. I don't talk about things that happen too much on the pitch. When you have an opportunity to [see it] you can have your own opinion."

The tie turned in Chelsea's favour after the second-half introduction of Hazard, and Benítez believes United are fortunate to be still in the competition. "I think so," he said.

Ferguson concurred. "We are lucky to still be in the FA Cup. We ran out of legs. Our two full-backs Rafael [da Silva] and Patrice Evra were just knackered. The two centre midfield players tired badly [Michael Carrick and Tom Cleverley] and we just kept giving the ball away.

"It made it a long day for us because we had to go from one penalty box and back to our own. They were by far the better team in the second half. We could have been maybe four up in the first 25 minutes of the match but I detected there was some signs of tiredness the way we were giving the ball away.

"When you see teams giving the ball away the way we were doing then you have to understand the problem is the emotions and intensity of Tuesday night had taken its toll on one or two of the players, understandably and I have no problems with that part."

Regarding Nani coming off before the break, Ferguson said: "Nani got a hamstring. I don't think it is serious but he had to come off. It was unfortunate because he was playing well."

On when the replay might take place he joked: "I don't know when, probably May! I don't know where it will be played."

A 0-0 draw on Sunday involving Millwall and Blackburn Rovers means they, too, must replay (on Wednesday), with Wigan Athletic awaiting the winners. Whichever team reaches the final from that half of the draw is all but guaranteed a Europa League place next season.